Demetalation of hydrocarbon oils



United States Patent DEMETALATION OF HYDROCARBON OILS William E Garwood, Haddonfield, N. 1., assignor to So- $13]; Mobil Oil Company, Inc., a corporation of New Application January 6, 1953, Serial No. 329,872 12 Claims. (Cl. 196-35) when oils containing the same are used as charging stocks f to catalytic cracking operations. Thus, in catalytic cracking operations as heretofore carried out, it has, in most cases, been necessary to use gas oil or other distillate as the charging stock. One important factor which has prevented the use of crude oils is that, with the use of such feed stocks, the catalyst rapidly deteriorates. Most crude oils contain metal contaminants, such as compounds of vanadium, nickel, iron, and copper, the nature of which have not been fully established, and compounds of other metals. These metal compounds, while present in only very minute amount, are corrosive and are responsible for the catalyst deterioration, which is expe rienced when petroleum crudes are used as charging stock to catalytic cracking operations. The economic difierence between the use of such materials as gas oil and reduced crude oil as charging stocks for crackingoperations is substantial. The present operation provides improvements which permit the use of a crude oil as charging stock for catalytic cracking operations.

Another important application of the present inven tion relates to removing metal contaminant from residuums resulting from the distillation of a crude petroleum oil. The residuums of the distillation operation are ordinarily employed as a bunker fuel or the like. The residuums, however, generally contain appreciable quan titles of heavy metals such ascopper, nickel, vanadium, and iron, as well as other metals or metal compounds introduced during various refining operations to which the residuum may have been subjected; The presence of metals in the oil gives rise to variousdifiiculties in the furnace in which it is burned as a fuel. Consequently, it is necessary to remove substantially all of the metal contaminant contained in the oil, and the present invention, as hereinabove indicated, provides a method for removing such contaminant.

Another adaptation of the present invention involves removing residual copper from hydrocarbon oils, such as gasoline, kerosene, light gas oil, and the like by the so-called copper-sweetening process. In the copper sweetening of hydrocarbon oils, the fuel on containing mercapta'ns and other undesirable sulfur compounds is contacted in liquid phase with a clay impregnated with cupric chloride in the presence of an oxidizing gas such as air or oxygen. In a similarcoppensweetening process, the fuel oil is treated with a solution containing copper ions. Both of theseprocesses are objectionable in that minor amounts of coppercompounds'are contained in 2,729,593 Patented Jan. 3, 1956 the treated oil. These minor amounts of copper accelerate gum formation and also accelerate the production of color-forming bodies in the oil. it has heretofore been proposed to remove these minor amounts of copper compounds by treating the sweetened oil with sodium sulfide or other salt. The process of the instant invention provides an improved effective means for removing the copper compounds from the oil.

In accordance with the present invention, it has been discovered that treatment of hydrocarbon oils containing metal contaminant with iodine, hydriodic acid and mixtures thereof provides a highly selective means for removing such contaminant with conversion of the metals present to the corresponding iodides. The resulting iodides are readily separated from the oil by filtration, settling, centrifuging, or the like and the resulting oil is substantially free from metal contaminant.

The treating reagent of iodine or hydriodic acid may be brought into contact with the metal contaminated-oil in any suitable manner. Advantageously, iodine is added as a solid while hydriodic acid is used as an aqueous solution although it may be used as a solution in a low molecular weight alcohol or other solvent. It is particularly desirable to employ aqueous constant boiling hydriodic acid containing about 55 per cent HI. The temperature used in the treatment must be maintained within the approximate range of 500 F. to 850 F. Below about 500 F, substantially no demetalation takes place, while at temperatures in excess of 850 F., appreciable cracking or degradation of the hydrocarbon stock takes place, resulting in a lower liquid recovery and higher gasmake with little additional demetalation. In particular, it is desirable to employ a temperature between about 650 F. and about 750 F. The pressure may vary Widely, depending upon the particular oil stock undergoing treatment and the temperature used and may range from atmospheric to 6000 pounds per square inch. The time of reaction is dependent largely on the particular temperature employed and may range from 0.01 to 10 hours, longer reaction times being employed with the use of lower temperatures.

The amount of iodine, hydriodic acid or mixtures thereof required as reagent for the removal of metal contaminants from the oil is theoretically slightly in excess of one equivalent of reagent for each equivalent of metal. The amount of such reagent employed accordingly depends on the extent of metal contaminant contained in the oil. It is usually advantageous to use an excess of reagent and to recover the unused portion thereof and recycle it until it is consumed. The amount of reagent, i. e. iodine or bydriodic acid, employed is generally between about 0.1 and about 30 per cent by weight, and preferably between about 1 and about 15 per cent by weight, of the oil undergoing treatment. Solutions of iodine in hydriodic acid may also be used with advantage in the present process. Under such conditions of operation, the concentration of iodine in 55 per cent aqueous hydriodic acid solution is preferably between about 40 and about 60 per cent by weight. With the use of iodine, the presence of hydrogen in the reaction mixture was found to increase liquid recovery and to increase the extent of demetalation. Under such conditions of operation it is desirable to employ hydrogen in an amount sufficient to maintain the hydrocarbon oil in liquid phase and preferably between about and about. 3000 p. s. i. g. pressure.

The operation may be carried out batch-wise by thoroughly mixing the oil with the hydriodic acid or iodine reagent under the above specified conditions and permitting the resulting reaction product mixture to settle, separating the oil from the'acid and tarry metal salt precipitate and using the recovered reagent until it is exhausted.

The operation may also be carried out continuously, as

by passing the oil and reagent into a reactor and heating under the desired conditions of temperature, pressure, and time. The resulting mixture of oil, and metal iodides together with any excess reagent is passed to suitable separators, such as settlers, centrifuges, filters, or the like to' separate the oil from the tarry metal salt precipitate.

Apparatus suitable for such an operation is illustrated diagrammatically in the appended drawing. In the drawing, 10 represents a reactor. The oil to be treated is introduced through inlet 11 and the reagent, for example, hydriodie acid through the inlet 12. The hydricdic acid and the oil are brought into intimate contact in the reactor at an elevated temperature and the products resulting from this heat treatment are removed from the reactor through outlet 13 and pass into settling tank 14 where the oil separates from the acid and the salts. The separated oil is removed from the settling tank through conduit 15 and passes into a wash tank 16 wherein it is washed free of hydriodic acid with water introduced through conduit 17. The washed oil, substantially free of metal contaminant, is withdrawn through outlet 18 and the wash water, containing soluble matter, is Withdrawn through. outlet 19. The hydriodic acid and the metal iodides are removed from the bottom of settling tank 14 byconduit 20 and are conducted to a filter 21 in which the metal salt precipitate is removed. The hydriodic acid is withdrawn from filter 21 and recycled through conduit 22 to reactor 10. The wash water containing dissolved hydriodic acid, passing through outlet conduit 19 is also recycled via conduit 22 to reactor 10. Make-up hydriodic acid is supplied to conduit 22 through line 23. Iodine and solutions of iodine in hydriodic acid may likewise be used in continuous operation.

The demetalation obtained with the use of hydriodic acid, iodine, or solutions of iodine in hydriodic acid in accordance with the present process is unique in its effectiveness in comparison with the extent of demetalation obtained with other halides or hydrogen halide solutions. Thus, in comparable runs and at the same yield level, hydriodic acid removed 99 per cent of nickel and vanadium contaminant present in a hydrocarbon oil, while treatment of the same oil with a hydrochloric or hydrofiuoric acid removed only about 70 per cent of the nickel and vanadium contaminant. The use of hydriodic acid for demetalation under conditions of the present invention accordingly provides an unexpectedly higher selective removal of metal contaminant than either hydrofluoric or hydrochloric acid. The following examples will serve to illustrate the process of the invention without limiting the same:

EXAMPLE 1 A /2-liter stainless steel rocking type bomb was charged with 178 grams (200 cc.) of a crude petroleum oil and 36 grams of an aqueous 55 per cent hydriodic acid solution.

The crude oil had an initial boiling point of 170 F., a

specific gravity of 0.9129, and a bromine number of 14.4, and contained the following metal contaminants:

Nickel, p. p. m 47 Vanadium, p. p m 58 Iron, p. p m 28 Copper, p. p. m 2

The head of the bomb was secured and the bomb was pressured to 1000 p. s. i. g. with nitrogen to test for leaks.

Hydrogen 17.1 Methane 38.8

Czs 22.1

Mole per cent Css 11.0 C4s 5.2 Cs 1.7 Css 0.5

The head was removed from the bomb and 161 grams of 7 liquid product consisting of 6 cc. of aqueous layer and 180 cc. of oil layer were decanted. The oil layer was extracted three times with 250 cc. portions of water. The 178 cc. of resulting raflinate, representing the treated oil, was dried, filtered, and found to have the following analysis:

Specific gravity 0.8665 Bromine No l2 Nickel, p. p. m 0.3 Vanadium, p.p. m 0.2 Iron, p. p. m 1.3 Copper, p. p. m 1.6

Finally, 49 grams of wet tarry precipitate was scraped from the bottom of the bomb. The recovery of liquid hydrocarbon oil was accordingly 89 volume per cent and the over-all reduction in metal contaminant was 97 per cent.

The following examples were carried out using the general procedure and hydrocarbon oil stock of Example 1 under varying conditions of temperature and pressure. The treating conditions and results are set forth in Table I below:

Table I Percent Re- HI Wt Volume moval oi Ex- P61106116 Temp., Time, Pressure, Percent ample of on F. Hrs. p. s. l. g. Re- V cover ana- Nickel dim It is to be noted from the above data that the extent of demetalation increased with an increase in reaction temperature with little of the metal contaminant being Two hundred cc. of a residuum resulting from distillation of a crude petroleum oil was contactedin a bomb with 81 grams of 55 per cent aqueous hydriodic acid solution. The oil had an initial boiling point of 515 F., a specific gravity of 0.9861, and contained 70.8 p. pm. of nickel and 71 p. p. m. of vanadium. The reaction mixture was maintained at a temperature of 700 F. for 2 hours, the maximum pressure being 700 p. s. i. g. At the completion of the reaction, cc. of liquid hydrocarbon product was obtained, representing a volume per cent recovery of 97.5 per cent. The treated hydrocarbon oil had the following analysis:

Specific gravity 1.0021 Nickel, p. p. m 41 Vanadium, p. p. m 57 EXAMPLE 6 Six hundred cc. of the crude petroleum oil described in Example 1 were charged to a rocking type bomb together with 12.5 grams of iodine dissolved in 7.5 grams of 55 per cent aqueous hydriodic acid solution. The

reaction mi mre in these-i t) was heated re a temperature of 700 F. for 2 hours, the maxiinumpressurebein 275 The removal of nickel, was accordingly 62 per cent, vanadium 80 per cent, and iron 97 per; cent.

The high metal content of the crude oil employed in this example makes catalytic cracking thereof. impractical due to catalyst poisoning.

However, after treatment, inlaec'ordance with. the procedure of this example, the liquid hydrocarbon product could be efiectively cracked. Upon using the treated bydrocarbon oil product as feedin a catalytic crackingoperation carried out at a temperature of 850 F., a space velocity of 1.5, and employinga catalyst to oil ratio of 4, using a silica-alumina cracking catalyst, the following results were obtained:

Gas, weight per cent 7.3 Coke, weight per cent 7.7 300 F., E. P. gasoline, per cent volume 24.4 410 F., E. P. gasoline, per cent volume 41.7 Cycle stock, volume 47.0

The use of iodine in effecting demetalation in accordance with the present process is illustrated by the following example:

EXAMPLE 7 One hundred fifty cc. of the crude petroleum oil described in Example 1 were charged to a rocking type bomb together with 15 grams of iodine. The reaction mixture in the bomb was heated to a temperature of approximately 700 F. for 2 hours, the maximum pressure being 1300 p. s. i. g. At the completion of the reaction, the liquid hydrocarbon product was removed, and filtered through paper. The resulting treated oil in the amount of 90 cc., representing a volume per cent recovery of 60 per cent, was found to have the following analysis:

Specific gravity 0.8453 Bromine No 7.1 Nickel, p. p. m 0.1 Vanadium, p. pQm 0.5 Iron, p. p. m- 6.4

The removal of nickel was accordingly practically 100 percent, vanadium 99 per cent and iron 81 per cent.

The following example illustrates the use of iodine, in the presence of hydrogen for etfecting removal of metal contaminant.

EXAMPLE 8 a volume per cent recovery of 92 per cent, was found to have the following analysis:

Specific gravity 0.8591 Bromine No l8 Nickel, p. p. 111 0.2 Vanadium, p. p. m 0.4 Iron, p. p. m i 0.8

action in an atmosphere of hydrogen, as will be notedfrom Example 8 served to improve the overall removal of metal contaminant and the volume per centrecovery of product.

I claim:

1. In a process involving pretreatment of crude petroleum oil containing metal compounds and subsequent use of the pretreated crude petroleum oil as a charging stock in a catalytic cracking operation, the improvement which comprises subjecting the crude petroleum oil in the pretreating operation and prior to bringing the oil into contact with the cracking catalyst to intimate admixture at a temperature between about 500 F. and about 850 F. with a reagent selected from the group consisting of iodine, hydriodic acid and mixtures thereof, whereby the metal compounds initially present in the crude petroleum oil react with said reagent to form the corresponding iodides, and separating the resulting iodides from the oil.

2. A process for removing metal contaminant selected from the group consisting of nickel, vanadium, iron, and copper from a hydrocarbon oil containing the same, which comprises contacting said oil with a reagent selected from the group consisting of iodine, hydriodic acid and mixtures thereof at a temperature of at least about 500 F., but below a temperature at which substantial conversion of said oil to lighter products occurs.

3. A process for removing metal contaminant selected from the group'consisting of nickel, vanadium, iron, and copper from a hydrocarbon oil containing the same, which comprises contacting said oil at a temperature between about 650 F. and about 750 F. with a reagent selected from the group consisting of iodine, hydriodic acid and mixtures thereof.

4. A process of refining a hydrocarbon oil for the purpose of removing metal ions contained therein in minor quantities, which comprises contacting said oil at a temperature between about 500 F. and about 850 F. with a reagent selected from the group consisting of iodine, hydriodic acid and mixtures thereof.

5. A process for treating a hydrocarbon oil contaminated with dissolved, catalytically active compounds selected from the group consisting of nickel, vanadium, iron, and copper, which comprises contacting said oil at a temperature between about 500 F. and about 850 F. with between about 0.1 and about 30 per cent by weight of a reagent selected from the group consisting of iodine, hydriodic acid and mixtures thereof.

6. A process for treating a hydrocarbon oil contaminated with dissolved, catalytically active compounds selected from the group consisting of nickel, vanadium, iron, and copper, which comprises contacting said oil at a temperature between about 650 F. and about 750 F. with between about 1 and about 15 per cent by weight of a reagent selected from the group consisting of iodine, hydriodic acid and mixtures thereof.

7. A process for removing residual copper from a hydrocarbon oil previously subjected to copper-sweetening, which comprises contacting said oil at a temperature of at least about 500 F., but below a temperature at which substantial conversion of said oil to lighter products occurs, with a reagent selected from the group consisting of iodine, hydriodic acid and mixtures thereof.

8. A process for removing trace metals from crude petroleum, which comprises contacting the crude petroleum stock at a temperature between about 500 F. and about 850 F. with aqueous constant boiling hydriodic acid to form the corresponding metal iodides, and separating the resulting iodides from the crude petroleum stock.

9. A process for removing metal contaminant from a hydrocarbon oil containing the same, which comprises contacting said oil with between about 0.1 and about 30 per centby weight of iodine at a temperature between about 500 F. and about 850 F. to form the corresponding metal iodides, and separating the resulting iodides from the oil.

10. A process for removing metal contaminant from a hydrocarbon oil containing the same, which comprises contacting said oil with between about 0.1 and about 30 per-cent by weight of iodine in the presence of between about 100 and about 3000 p. s. i. g. pressure of hydrogen at a temperature between about 500 F. and about 850 F. to form the corresponding metal iodides, and separating the resulting iodides from the oil. 7

11. A continuous process for effecting demetalation of a hydrocarbon oil containing metal contaminant, which comprises contacting said oil at a temperature between about 500' F. and about 850 F. with a reagent selected.

from the group consisting of iodine, hydriodic acid and a hydriodic acid solution of iodine, separating the resulting oil substantially free of metal contaminant from excess reagent and'a residual tarry precipitate, separating the tarry precipitate from said reagent and recycling the latter to contact with a charge of the original oil.

12. A continuous process for effecting demetalation of a hydrocarbon oil containing metal contaminant, which comprises contacting said oil at a temperature of at least about 500 F., but below a temperature at which substantial conversion of said oil to lighter products occurs, with an excess of hydriodic acid, separating the treated oil from the excess hydriodic acid and a residual tarry precipitate, washing the treated oil to remove hydriodic acid therefrom, separating the tarry precipitate from excess hydriodic acid, combining the latter with the effiuent resulting from washing the treated oil, and recycling the resulting combined stream of hydriodic acid to contact with a charge of the original oil.

References Cited in the file of this patent UNITED STATES PATENTS 74,756 Flowers Feb. 25, 1868 1,843,516 Oberle Feb. 2, 1932 2,174,810 Von Fuchs et a1 Oct. 3, 1939 

2. A PROCESS FOR REMOVING METAL CONTAMINANT SELECTED FROM THE GROUP CONSISTING OF NICKEL, VANADIUM, IRON, AND COPPER FROM A HYDROCARBON OIL CONTAINING THE SAME, WHICH COMPRISES CONTACTING SAID OIL WITH A REAGENT SELECTED FROM THE GROUP CONSISTING OF IODINE, HYDRIODIC ACID 